14deb585fb
The size and padding of `struct object_entry` is an important factor in determining the memory usage of `pack-objects`. For this reason,3b13a5f263(pack-objects: reorder members to shrink struct object_entry, 2018-04-14) added a comment containing some information from pahole indicating the size and padding of that struct. Unfortunately, this comment hasn't been updated since9ac3f0e5b3(pack-objects: fix performance issues on packing large deltas, 2018-07-22), despite the size of this struct changing many times since that commit. To see just how often the size of object_entry changes, I skimmed the first-parent history with this script: for sha in $(git rev-list --first-parent --reverse 9ac3f0e..) do echo -n "$sha " git checkout -q $sha make -s pack-objects.o 2>/dev/null pahole -C object_entry pack-objects.o | sed -n \ -e 's/\/\* size: \([0-9]*\).*/size \1/p' \ -e 's/\/\*.*padding: \([0-9]*\).*/padding \1/p' | xargs done | uniq -f1 In between each merge, the size of object_entry changes too often to record every instance here. But the important merges (along with their corresponding sizes and bit paddings) in chronological order are:ad635e82d6(Merge branch 'nd/pack-objects-pack-struct', 2018-05-23) size 80 padding 429d9e3e2c4(Merge branch 'nd/pack-deltify-regression-fix', 2018-08-22) size 80 padding 93ebdef2e1b(Merge branch 'jk/pack-delta-reuse-with-bitmap', 2018-09-17) size 80 padding 833e4ae9c50(Merge branch 'bc/sha-256', 2019-01-29) size 96 padding 8 (indicating that the current size of the struct is 96 bytes, with 8 padding bits). Even though this comment was written in a good spirit, it is updated infrequently enough that it serves to confuse rather than to encourage contributors to update the appropriate values when the modify the definition of object_entry. For that reason, eliminate the confusion by removing the comment altogether. Signed-off-by: Taylor Blau <me@ttaylorr.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git - fast, scalable, distributed revision control system
Git is a fast, scalable, distributed revision control system with an unusually rich command set that provides both high-level operations and full access to internals.
Git is an Open Source project covered by the GNU General Public License version 2 (some parts of it are under different licenses, compatible with the GPLv2). It was originally written by Linus Torvalds with help of a group of hackers around the net.
Please read the file INSTALL for installation instructions.
Many Git online resources are accessible from https://git-scm.com/ including full documentation and Git related tools.
See Documentation/gittutorial.txt to get started, then see
Documentation/giteveryday.txt for a useful minimum set of commands, and
Documentation/git-<commandname>.txt for documentation of each command.
If git has been correctly installed, then the tutorial can also be
read with man gittutorial or git help tutorial, and the
documentation of each command with man git-<commandname> or git help <commandname>.
CVS users may also want to read Documentation/gitcvs-migration.txt
(man gitcvs-migration or git help cvs-migration if git is
installed).
The user discussion and development of Git take place on the Git mailing list -- everyone is welcome to post bug reports, feature requests, comments and patches to git@vger.kernel.org (read Documentation/SubmittingPatches for instructions on patch submission and Documentation/CodingGuidelines).
Those wishing to help with error message, usage and informational message
string translations (localization l10) should see po/README.md
(a po file is a Portable Object file that holds the translations).
To subscribe to the list, send an email with just "subscribe git" in the body to majordomo@vger.kernel.org (not the Git list). The mailing list archives are available at https://lore.kernel.org/git/, http://marc.info/?l=git and other archival sites.
Issues which are security relevant should be disclosed privately to the Git Security mailing list git-security@googlegroups.com.
The maintainer frequently sends the "What's cooking" reports that list the current status of various development topics to the mailing list. The discussion following them give a good reference for project status, development direction and remaining tasks.
The name "git" was given by Linus Torvalds when he wrote the very first version. He described the tool as "the stupid content tracker" and the name as (depending on your mood):
- random three-letter combination that is pronounceable, and not actually used by any common UNIX command. The fact that it is a mispronunciation of "get" may or may not be relevant.
- stupid. contemptible and despicable. simple. Take your pick from the dictionary of slang.
- "global information tracker": you're in a good mood, and it actually works for you. Angels sing, and a light suddenly fills the room.
- "goddamn idiotic truckload of sh*t": when it breaks